1. Field of the Invention
The invention relates to a built-in plug with a grounding wire contact pin which projects on the plug side and which is located in a plug housing forming a connection receptacle.
2. Description of Related Art
Built-in plugs of the aforementioned type are already known as part of plug connections. These built-in plugs are used for electronic and electrical parts of any type, for example, for proximity switches. The structure of these built-in plugs is generally always the same. Thus, normally several active contact pins together with a grounding wire contact pin, which is normally leading on the plug side, are provided. Moreover, known built-in plugs generally have a cable box with a gasket and union nut. The grounding wire contact pin thus penetrates the built-in plug, i.e., it is accessible on the plug and on the solder side. On the solder side, this contact pin must then be continued through a second or third part up to the so-called "accessible" surface as a protective contact and must be connected to the latter.
Known built-in plugs have a series of, in part, significant disadvantages. Thus, for example, the VDE-compatible creepage distances and clearances are in part largely not achieved. The inadequate creepage distances and clearances are caused especially by the fact that the active pins and grounding wire contact pin on the solder side are located too close to one another due to a fixed and stipulated connection pattern. As the result of deviations from the required setpoints of the creepage distances and clearances, various of the known built-in plugs do not satisfy requirements of safety class I (according to IEC 536, DIN VBE 0106T, 1A1) and thus represent a safety risk.
Furthermore, built-in plugs are known from practice in which the grounding wire contact pin is pressed onto the housing to be protected only in conjunction with a plastic pin carrier. In case of a fault, specifically when the plastic insert softens due to heat, the pressure force is cancelled and thus also grounding wire contacting.
Additionally, various mechanical problems exist in known built-in plugs. One fundamental problem is that different built-in plugs do not have sufficient torsional resistance. This means that, when the plug is twisted, there is the danger that an active pin will come into contact with the grounding wire contact pin, by which equipment safety suffers. To prevent this problem, specially designed mounting sleeves and adapters are necessary which are designed to guarantee mechanical torsion resistance. Besides the additional individual parts necessary for this purpose, costs are also higher.
Moreover, another problem consists in that the installation process, when assembling the built-in plug, is not inherently reproducible since contact of the grounding wire contact pin with the housing is generally closed by soldering. Moreover, in this type of connection of the grounding wire contact pin to the housing, there is no adequate checking whether soldering always satisfies the thermal and mechanical requirements in case of a fault. Finally, many built-in plugs have no plug vent, by which complete sealing of the pertinent parts, for example, of proximity switches, becomes impossible.